This invention relates to millimeter wave radars and more particularly to a frequency modulated continuous wave (FMCW) sequential lobing tracking radar for tracking vehicles on a roadway. Still more particularly the invention relates to radar information storage and processing as applied to an automobile radar.
Automobile movement occurs every day on the world's roadways. In long trips it is often desirable to use a feature of an automobile commonly referred to as cruise control wherein a predetermined speed of a vehicle is set by an operator and a cruise control system controls the vehicle to maintain the predetermined speed. Unfortunately, such a system requires the operator to manually override the cruise control system when conditions preclude the vehicle from traveling the predetermined speed.
With a radar system mounted in a vehicle, it would be possible to recognize an existence of other vehicles. Such a radar would need to be able to distinguish moving vehicles from one another as well as from other objects typically found along a roadway. With a radar system mounted in the vehicle, guidance control signals can be fed to a cruise control system to more efficiently control the speed of the vehicle.
In a typical FMCW radar the transmitted waveform includes a positive slope frequency ramp, a negative slope frequency ramp and an interval of constant frequency (CW burst). In a sequential lobing tracking system, the waveform is repeated for each antenna lobe in sequence. The radar return in each antenna lobe is processed by a positive going ramp FFT (Fast Fourier Transform), a negative going ramp FFT and a CW burst FFT, and combined in a composite tracker to provide a range, a range rate, an acceleration and an angle associated with the target.